The LEICA M7 is a manual-focus rangefinder, automatic electronic-shutter 35mm full-frame camera.
It has both manual and aperture-preferred auto exposure modes and works with all LEICA M lenses and accessories made since 1954.
"Rangefinder" means that you focus by lining-up a superimposed image in a separate viewfinder. That's the window on the top right.
Unlike SLRs, you are looking through a separate viewfinder, not through the lens. This lets rangefinder cameras weigh much less, have sharper optics, vibrate less and make less noise than SLRs which require additional prisms, mirrors and mechanics, but it also means that you can't compose anywhere near as accurately as you can with an SLR because you're never looking through the lens. This is why rangefinder cameras went obsolete overnight in the 1960s. Leica continues to make these for a minority of people who prefer small, quiet, simple cameras with superb optics over the convenience and precise composition of SLRs.